I have two database called DB1 and DB2.
I have one table called T1 in DB1.
I created a snapshot T2 in DB2 for T1 by using Database Link.
I have sheduled the refresh group for every 5 seconds.
I have created one Scheduled link for my database link every 5 secconds.
Now I can able see the data from DB1.T1 through DB2.T2 snapshot.
And the refreshing is also working fine.
The problem is every five seconds it refresh the data.
So when I select the data from DB2.T2 some times data missing. It comes after few seconds...
I think for that refreshing it remove the data from DB2.T2 and again inserts.
So I could't see the data continousely.
it is definetly deleting data.
Now I forgot, but I believe that in complete refresh mode it just truncates table => for a while another session see zero rows.
Can be easily tested with dbms_snapshot.refresh(,, 'C')